The initial population of bacteria in a lab test is 400. the number of bacteria doubles every 30 minutes. predict the bacteria population at the end of three hours

Pls , the question is in the picture!

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online

Ill mark the brainliest if you me with the these three questions 7,8,9